From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3132EC61DA3 for ; Tue, 21 Feb 2023 02:38:25 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id B1A1E400CC; Tue, 21 Feb 2023 02:38:24 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org B1A1E400CC Authentication-Results: smtp2.osuosl.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Qpyn/DRa X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id s5vfdSQy5Rru; Tue, 21 Feb 2023 02:38:23 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTPS id 1CAC44012A; Tue, 21 Feb 2023 02:38:23 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 1CAC44012A Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id C6810C0032; Tue, 21 Feb 2023 02:38:22 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 765EAC002B for ; Tue, 21 Feb 2023 02:38:21 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 49C44700D9 for ; Tue, 21 Feb 2023 02:38:21 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 49C44700D9 Authentication-Results: smtp3.osuosl.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Qpyn/DRa X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5nzcV2wYWJwE for ; Tue, 21 Feb 2023 02:38:20 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 3675C6FFE9 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by smtp3.osuosl.org (Postfix) with ESMTPS id 3675C6FFE9 for ; Tue, 21 Feb 2023 02:38:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1676947098; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=O1eETGbsNJ3o4GhZE8orvsa9aWlXBtgkGSwcd3OHgbs=; b=Qpyn/DRa24FN5Q0osHpA3pvuIO08RfoSU2RdhsJXYgFvlxvErfWOmO5L/EYkCu0+79R2mE zpVhiu22Io7MV0gLraifmTyTsdlJjow/U1fXlhLndt7eJ/T50F8bYlTRTAEByJfIVjf4Ky UKye+JBVn/s9GZ97xjyWpuFBiyHEnGo= Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-137-quVOgpMdOw2rz5ZiD_eoGg-1; Mon, 20 Feb 2023 21:38:17 -0500 X-MC-Unique: quVOgpMdOw2rz5ZiD_eoGg-1 Received: by mail-pg1-f198.google.com with SMTP id q68-20020a632a47000000b004f74bc0c71fso916951pgq.18 for ; Mon, 20 Feb 2023 18:38:17 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=O1eETGbsNJ3o4GhZE8orvsa9aWlXBtgkGSwcd3OHgbs=; b=pzKZ9cVuAjTNEyoVFOWxpK8eqC4hhdWmYyitpdmOLkzLaqSxtR+batEkb/iOvXTt4a HbtbPvJnqwt1dW+cQ06PF+OvylmW5PK64o/9js1l0OvbA8yP7N+mKWVASkcgUxja1gMa 0HXuz9vjbTb8vKwCgKaIJ/teqzdu4CgE5sTTq1qezT5hfYAnrT0yofLCXruBXlc1otUu XJWKjdEvKlF8/FJGdQoSwsI9tN/JZGVSspCQqEM3Sp6LGk6qcvMqxNElP9AUTHw1bNAq LMdPPPSzL3a98EJK1JbOe7c6snpCsZHWjXzt7N55Pk9BUBeUk/ak6MbehRS4OmUOVDqO WJWw== X-Gm-Message-State: AO0yUKVnKAqy9ApHwW6410OGauGX6cE4uvbXgN1e4qc1j4zBZLtaQtaf YK0IfHV1X65YxzfQT8mWE0n4qx6cnSpv0xHhCPgS9pORRyqexu4tqswlVgbvmGa9HViG01tCwzU nvOTg8a8aDaOK+LQ4cC305OTxC1drFzzCKsfCgZcDYQ== X-Received: by 2002:a05:6a20:3ca0:b0:be:e0c3:5012 with SMTP id b32-20020a056a203ca000b000bee0c35012mr2696231pzj.1.1676947096339; Mon, 20 Feb 2023 18:38:16 -0800 (PST) X-Google-Smtp-Source: AK7set/720MKakE5XCGQ7Uh5rmW8ucJCIgp1rd9sNEeFmTZV4diZNLLhb5dWRXWL+38RQ13GmZ68VA== X-Received: by 2002:a05:6a20:3ca0:b0:be:e0c3:5012 with SMTP id b32-20020a056a203ca000b000bee0c35012mr2696208pzj.1.1676947095997; Mon, 20 Feb 2023 18:38:15 -0800 (PST) Received: from [10.72.13.11] ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id i26-20020aa78b5a000000b005a8e9e2f1c5sm845882pfd.187.2023.02.20.18.38.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Feb 2023 18:38:15 -0800 (PST) Message-ID: Date: Tue, 21 Feb 2023 10:38:10 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [patch net-next] net: virtio_net: implement exact header length guest feature To: Jiri Pirko , "Michael S. Tsirkin" References: <20230217121547.3958716-1-jiri@resnulli.us> <20230217072032-mutt-send-email-mst@kernel.org> <20230217083915-mutt-send-email-mst@kernel.org> <20230220074947-mutt-send-email-mst@kernel.org> From: Jason Wang In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Cc: Vitaly Mireyno , netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" CuWcqCAyMDIzLzIvMjAgMjE6NTYsIEppcmkgUGlya28g5YaZ6YGTOgo+IE1vbiwgRmViIDIwLCAy MDIzIGF0IDAxOjU1OjMzUE0gQ0VULCBtc3RAcmVkaGF0LmNvbSB3cm90ZToKPj4gT24gTW9uLCBG ZWIgMjAsIDIwMjMgYXQgMDk6MzU6MDBBTSArMDEwMCwgSmlyaSBQaXJrbyB3cm90ZToKPj4+IEZy aSwgRmViIDE3LCAyMDIzIGF0IDAyOjQ3OjM2UE0gQ0VULCBtc3RAcmVkaGF0LmNvbSB3cm90ZToK Pj4+PiBPbiBGcmksIEZlYiAxNywgMjAyMyBhdCAwMTo1Mzo1NVBNICswMTAwLCBKaXJpIFBpcmtv IHdyb3RlOgo+Pj4+PiBGcmksIEZlYiAxNywgMjAyMyBhdCAwMToyMjowMVBNIENFVCwgbXN0QHJl ZGhhdC5jb20gd3JvdGU6Cj4+Pj4+PiBPbiBGcmksIEZlYiAxNywgMjAyMyBhdCAwMToxNTo0N1BN ICswMTAwLCBKaXJpIFBpcmtvIHdyb3RlOgo+Pj4+Pj4+IEZyb206IEppcmkgUGlya28gPGppcmlA bnZpZGlhLmNvbT4KPj4+Pj4+Pgo+Pj4+Pj4+IHZpcnRpb19uZXRfaGRyX2Zyb21fc2tiKCkgZmls bHMgdXAgaGRyX2xlbiB0byBza2JfaGVhZGxlbihza2IpLgo+Pj4+Pj4+Cj4+Pj4+Pj4gVmlydGlv IHNwZWMgaW50cm9kdWNlZCBhIGZlYXR1cmUgVklSVElPX05FVF9GX0dVRVNUX0hEUkxFTiB3aGlj aCB3aGVuCj4+Pj4+Pj4gc2V0IGltcGxpY2F0ZXMgdGhhdCB0aGUgZHJpdmVyIHByb3ZpZGVzIHRo ZSBleGFjdCBzaXplIG9mIHRoZSBoZWFkZXIuCj4+Pj4+Pj4KPj4+Pj4+PiBUaGUgZHJpdmVyIGFs cmVhZHkgY29tcGxpZXMgdG8gZmlsbCB0aGUgY29ycmVjdCB2YWx1ZS4gSW50cm9kdWNlIHRoZQo+ Pj4+Pj4+IGZlYXR1cmUgYW5kIGFkdmVydGlzZSBpdC4KPj4+Pj4+Pgo+Pj4+Pj4+IFNpZ25lZC1v ZmYtYnk6IEppcmkgUGlya28gPGppcmlAbnZpZGlhLmNvbT4KPj4+Pj4+IENvdWxkIHlvdSBhZGQg YSBiaXQgb2YgbW90aXZhdGlvbiBqdXN0IGZvciB0aGUgcmVjb3JkPwo+Pj4+Pj4gRG9lcyB0aGlz IGltcHJvdmUgcGVyZm9ybWFuY2UgZm9yIHNvbWUgY2FyZD8gQnkgaG93IG11Y2g/Cj4+Pj4+PiBF eHBlY3RlZCB0byBoZWxwIHNvbWUgZnV0dXJlIGNhcmQ/Cj4+Pj4+IEkgY2FuIGdldCB0aGF0IGlu Zm8sIGJ1dCBpc24ndCB0aGF0IHJhdGhlciBzb21ldGhpbmcgdG8gYmUgYXBwZW5kZWQgdG8KPj4+ Pj4gdGhlIHZpcnRpby1zcGVjIHBhdGNoPyBJIG1lYW4sIHRoZSBmZWF0dXJlIGlzIHRoZXJlLCB0 aGlzIGlzIGp1c3QKPj4+Pj4gaW1wbGVtZW50aW5nIGl0IGluIG9uZSBkcml2ZXIuCj4+Pj4gSXQg aXMgbW9yZSBsaWtlIHVzaW5nIGl0IGluIHRoZSBkcml2ZXIuICBJdCdzIG5vdCBsaWtlIHdlIGhh dmUgdG8gdXNlCj4+Pj4gZXZlcnl0aGluZyAtIGl0IGNvdWxkIGJlIHVzZWZ1bCBmb3IgZS5nLiBk cGRrIGJ1dCBub3QgbGludXguCj4+Pj4gSW1wbGVtZW50aW5nIGl0IGluIHRoZSBMaW51eCBkcml2 ZXIgaGFzIHN1cHBvcnQgY29zdHMgLSBmb3IgZXhhbXBsZSB3aGF0Cj4+Pj4gaWYgdGhlcmUncyBh IGJ1ZyBhbmQgc29tZXRpbWVzIHRoZSBsZW5ndGggaXMgaW5jb3JyZWN0Pwo+Pj4+IFdlJ2xsIGJl IGJyZWFraW5nIHRoaW5ncy4KPj4+IEkgdW5kZXJzdGFuZC4gVG8gbXkgdW5kZXJzdGFuZGluZyB0 aGlzIGZlYXR1cmUganVzdCBmaXhlcyB0aGUgb3JpZ2luYWwKPj4+IGFtYmlndWl0eSBpbiB0aGUg dmlydGlvIHNwZWMuCj4+Pgo+Pj4gUXVvdGluZyB0aGUgb3JpZ2luYWwgdmlydGlvIHNwZWM6Cj4+ PiAiaGRyX2xlbiBpcyBhIGhpbnQgdG8gdGhlIGRldmljZSBhcyB0byBob3cgbXVjaCBvZiB0aGUg aGVhZGVyIG5lZWRzIHRvCj4+PiAgIGJlIGtlcHQgdG8gY29weSBpbnRvIGVhY2ggcGFja2V0Igo+ Pj4KPj4+ICJhIGhpbnQiIG1pZ2h0IG5vdCBiZSBjbGVhciBmb3IgdGhlIHJlYWRlciB3aGF0IGRv ZXMgaXQgbWVhbiwgaWYgaXQgaXMKPj4+ICJtYXliZSBsaWtlIHRoYXQiIG9mICJleGFjdGx5IGxp a2UgdGhhdCIuIFRoaXMgZmVhdHVyZSBqdXN0IG1ha2VzIGl0Cj4+PiBjcnlzdGFsIGNsZWFyLgo+ Pj4KPj4+IElmIHlvdSBsb29rIGF0IHRoZSB0YXAgaW1wbGVtZW50YXRpb24sIGl0IHVzZXMgaGRy X2xlbiB0byBhbGxvYwo+Pj4gc2tiIGxpbmVhciBwYXJ0LiBObyBoaW50LCBpdCBjb3VudHMgd2l0 aCB0aGUgcHJvdmlkZWQgdmFsdWUuCj4+PiBTbyBpZiB0aGUgZHJpdmVyIGlzIGN1cnJlbnRseSBu b3QgcHJlY2lzZSwgaXQgYnJlYWtzIHRhcC4KPj4gV2VsbCB0aGF0J3Mgb25seSBmb3IgZ3NvIHRo b3VnaCByaWdodD8KPiBZZXAuCj4KPgo+PiBBbmQgbWFraW5nIGl0IGJpZ2dlciB0aGFuIG5lY2Vz c2FyeSB3b3JrcyBmaW5lIC4uLgo+IFdlbGwgeWVhaC4gQnV0IHRhcCBkb2VzIG5vdCBkbyB0aGF0 LCBkb2VzIGl0PyBpdCB1c2VzIGhkcl9sZW4gZGlyZWN0bHkuCgoKdGFwX2dldF91c2VyKCkgbGlt aXQgdGhlIGhlYWQgbGVuZ3RoOgoKCnN0YXRpYyBzc2l6ZV90IHRhcF9nZXRfdXNlcihzdHJ1Y3Qg dGFwX3F1ZXVlICpxLCB2b2lkICptc2dfY29udHJvbCwKIMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDC oMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoCBzdHJ1Y3QgaW92X2l0ZXIgKmZyb20sIGlu dCBub2Jsb2NrKQp7CiDCoMKgIMKgaW50IGdvb2RfbGluZWFyID0gU0tCX01BWF9IRUFEKFRBUF9S RVNFUlZFKTsKLi4uCgoKPgo+Cj4+PiBJIHdpbGwgYWRkIHRoaXMgdG8gdGhlIHBhdGNoIGRlc2Ny aXB0aW9uIGFuZCBzZW5kIHYyLgo+Pj4KPj4gSSBmZWVsIHRoaXMgZG9lcyBub3QgYW5zd2VyIHRo ZSBxdWVzdGlvbiB5ZXQsIG9yIG1heWJlIEkgYW0gYmVpbmcgZGVuc2UuCj4+IE15IHBvaW50IHdh cyBub3QgYWJvdXQgbWFraW5nIGhkcl9sZW4gcHJlY2lzZS4gIE15IHBvaW50IHdhcyB0aGF0IHdl IGFyZQo+PiBtYWtpbmcgYSBjaGFuZ2UgaGVyZSBmb3Igbm8gYXBwYXJlbnQgcmVhc29uLiBJIGFt IGd1ZXNzaW5nIHlvdSBhcmUgbm90Cj4+IGRvaW5nIGl0IGZvciBmdW4gLSBzbyB3aHk/IElzIHRo ZXJlIGEgZGV2aWNlIHdpdGggdGhpcyBmZWF0dXJlIGJpdAo+PiB5b3UgYXJlIGF3YXJlIG9mPwo+ IEFmYWlrIHJlYWwgaHcgd2hpY2ggZG9lcyBlbXVsYXRpb24gb2YgdmlydGlvX25ldCB3b3VsZCBi ZW5lZml0IGZyb20KPiB0aGF0LCBvdXIgaHcgaW5jbHVkaW5nLgoKCk5vdGUgdGhhdCBkcml2ZXIg Y2FuIGNob29zZSB0byBubyBuZWdvdGlhdGUgdGhpcyBmZWF0dXJlLCBzbyBtYWxpY2lvdXMgCmRy aXZlcnMgY2FuIHN0aWxsIHRyeSB0byB1c2UgaWxsZWdhbCB2YWx1ZS4KClRoYW5rcwoKCj4KPgo+ Pgo+Pgo+Pj4+IFRoZSBwYXRjaCB3YXMgc3VibWl0dGVkIGJ5IE1hcnZlbGwgYnV0IHRoZXkgbmV2 ZXIgYm90aGVyZWQgd2l0aAo+Pj4+IHVzaW5nIGl0IGluIExpbnV4LiBJIGd1ZXNzIHRoZXkgYXJl IHVzaW5nIGl0IGZvciBzb21ldGhpbmcgZWxzZT8KPj4+PiBDQyBWaXRhbHkgd2hvIHB1dCB0aGlz IGluLgo+Pj4+Cj4+Pj4+PiB0aGFua3MhCj4+Pj4+Pgo+Pj4+Pj4KPj4+Pj4+PiAtLS0KPj4+Pj4+ PiAgIGRyaXZlcnMvbmV0L3ZpcnRpb19uZXQuYyAgICAgICAgfCA2ICsrKystLQo+Pj4+Pj4+ICAg aW5jbHVkZS91YXBpL2xpbnV4L3ZpcnRpb19uZXQuaCB8IDEgKwo+Pj4+Pj4+ICAgMiBmaWxlcyBj aGFuZ2VkLCA1IGluc2VydGlvbnMoKyksIDIgZGVsZXRpb25zKC0pCj4+Pj4+Pj4KPj4+Pj4+PiBk aWZmIC0tZ2l0IGEvZHJpdmVycy9uZXQvdmlydGlvX25ldC5jIGIvZHJpdmVycy9uZXQvdmlydGlv X25ldC5jCj4+Pj4+Pj4gaW5kZXggZmI1ZTY4ZWQzZWMyLi5lODViMDM5ODg3MzMgMTAwNjQ0Cj4+ Pj4+Pj4gLS0tIGEvZHJpdmVycy9uZXQvdmlydGlvX25ldC5jCj4+Pj4+Pj4gKysrIGIvZHJpdmVy cy9uZXQvdmlydGlvX25ldC5jCj4+Pj4+Pj4gQEAgLTYyLDcgKzYyLDggQEAgc3RhdGljIGNvbnN0 IHVuc2lnbmVkIGxvbmcgZ3Vlc3Rfb2ZmbG9hZHNbXSA9IHsKPj4+Pj4+PiAgIAlWSVJUSU9fTkVU X0ZfR1VFU1RfVUZPLAo+Pj4+Pj4+ICAgCVZJUlRJT19ORVRfRl9HVUVTVF9DU1VNLAo+Pj4+Pj4+ ICAgCVZJUlRJT19ORVRfRl9HVUVTVF9VU080LAo+Pj4+Pj4+IC0JVklSVElPX05FVF9GX0dVRVNU X1VTTzYKPj4+Pj4+PiArCVZJUlRJT19ORVRfRl9HVUVTVF9VU082LAo+Pj4+Pj4+ICsJVklSVElP X05FVF9GX0dVRVNUX0hEUkxFTgo+Pj4+Pj4+ICAgfTsKPj4+Pj4+PiAgIAo+Pj4+Pj4+ICAgI2Rl ZmluZSBHVUVTVF9PRkZMT0FEX0dST19IV19NQVNLICgoMVVMTCA8PCBWSVJUSU9fTkVUX0ZfR1VF U1RfVFNPNCkgfCBcCj4+Pj4+Pj4gQEAgLTQyMTMsNyArNDIxNCw4IEBAIHN0YXRpYyBzdHJ1Y3Qg dmlydGlvX2RldmljZV9pZCBpZF90YWJsZVtdID0gewo+Pj4+Pj4+ICAgCVZJUlRJT19ORVRfRl9D VFJMX01BQ19BRERSLCBcCj4+Pj4+Pj4gICAJVklSVElPX05FVF9GX01UVSwgVklSVElPX05FVF9G X0NUUkxfR1VFU1RfT0ZGTE9BRFMsIFwKPj4+Pj4+PiAgIAlWSVJUSU9fTkVUX0ZfU1BFRURfRFVQ TEVYLCBWSVJUSU9fTkVUX0ZfU1RBTkRCWSwgXAo+Pj4+Pj4+IC0JVklSVElPX05FVF9GX1JTUywg VklSVElPX05FVF9GX0hBU0hfUkVQT1JULCBWSVJUSU9fTkVUX0ZfTk9URl9DT0FMCj4+Pj4+Pj4g KwlWSVJUSU9fTkVUX0ZfUlNTLCBWSVJUSU9fTkVUX0ZfSEFTSF9SRVBPUlQsIFZJUlRJT19ORVRf Rl9OT1RGX0NPQUwsIFwKPj4+Pj4+PiArCVZJUlRJT19ORVRfRl9HVUVTVF9IRFJMRU4KPj4+Pj4+ PiAgIAo+Pj4+Pj4+ICAgc3RhdGljIHVuc2lnbmVkIGludCBmZWF0dXJlc1tdID0gewo+Pj4+Pj4+ ICAgCVZJUlRORVRfRkVBVFVSRVMsCj4+Pj4+Pj4gZGlmZiAtLWdpdCBhL2luY2x1ZGUvdWFwaS9s aW51eC92aXJ0aW9fbmV0LmggYi9pbmNsdWRlL3VhcGkvbGludXgvdmlydGlvX25ldC5oCj4+Pj4+ Pj4gaW5kZXggYjQwNjJiZWQxODZhLi4xMmMxYzk2OTk5MzUgMTAwNjQ0Cj4+Pj4+Pj4gLS0tIGEv aW5jbHVkZS91YXBpL2xpbnV4L3ZpcnRpb19uZXQuaAo+Pj4+Pj4+ICsrKyBiL2luY2x1ZGUvdWFw aS9saW51eC92aXJ0aW9fbmV0LmgKPj4+Pj4+PiBAQCAtNjEsNiArNjEsNyBAQAo+Pj4+Pj4+ICAg I2RlZmluZSBWSVJUSU9fTkVUX0ZfR1VFU1RfVVNPNgk1NQkvKiBHdWVzdCBjYW4gaGFuZGxlIFVT T3Y2IGluLiAqLwo+Pj4+Pj4+ICAgI2RlZmluZSBWSVJUSU9fTkVUX0ZfSE9TVF9VU08JNTYJLyog SG9zdCBjYW4gaGFuZGxlIFVTTyBpbi4gKi8KPj4+Pj4+PiAgICNkZWZpbmUgVklSVElPX05FVF9G X0hBU0hfUkVQT1JUICA1NwkvKiBTdXBwb3J0cyBoYXNoIHJlcG9ydCAqLwo+Pj4+Pj4+ICsjZGVm aW5lIFZJUlRJT19ORVRfRl9HVUVTVF9IRFJMRU4gIDU5CS8qIEd1ZXN0IHByb3ZpZGVzIHRoZSBl eGFjdCBoZHJfbGVuIHZhbHVlLiAqLwo+Pj4+Pj4+ICAgI2RlZmluZSBWSVJUSU9fTkVUX0ZfUlNT CSAgNjAJLyogU3VwcG9ydHMgUlNTIFJYIHN0ZWVyaW5nICovCj4+Pj4+Pj4gICAjZGVmaW5lIFZJ UlRJT19ORVRfRl9SU0NfRVhUCSAgNjEJLyogZXh0ZW5kZWQgY29hbGVzY2luZyBpbmZvICovCj4+ Pj4+Pj4gICAjZGVmaW5lIFZJUlRJT19ORVRfRl9TVEFOREJZCSAgNjIJLyogQWN0IGFzIHN0YW5k YnkgZm9yIGFub3RoZXIgZGV2aWNlCj4+Pj4+Pj4gLS0gCj4+Pj4+Pj4gMi4zOS4wCgpfX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpWaXJ0dWFsaXphdGlvbiBt YWlsaW5nIGxpc3QKVmlydHVhbGl6YXRpb25AbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0 cHM6Ly9saXN0cy5saW51eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vdmlydHVhbGl6 YXRpb24= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07007C636D6 for ; Tue, 21 Feb 2023 02:39:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233048AbjBUCje (ORCPT ); Mon, 20 Feb 2023 21:39:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233046AbjBUCjd (ORCPT ); Mon, 20 Feb 2023 21:39:33 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 056AB211C7 for ; Mon, 20 Feb 2023 18:38:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1676947098; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=O1eETGbsNJ3o4GhZE8orvsa9aWlXBtgkGSwcd3OHgbs=; b=Qpyn/DRa24FN5Q0osHpA3pvuIO08RfoSU2RdhsJXYgFvlxvErfWOmO5L/EYkCu0+79R2mE zpVhiu22Io7MV0gLraifmTyTsdlJjow/U1fXlhLndt7eJ/T50F8bYlTRTAEByJfIVjf4Ky UKye+JBVn/s9GZ97xjyWpuFBiyHEnGo= Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-571-fZMcsJh-NHCIN1dws4EyYQ-1; Mon, 20 Feb 2023 21:38:17 -0500 X-MC-Unique: fZMcsJh-NHCIN1dws4EyYQ-1 Received: by mail-pg1-f199.google.com with SMTP id o38-20020a635d66000000b004fbec68e875so843040pgm.1 for ; Mon, 20 Feb 2023 18:38:17 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=O1eETGbsNJ3o4GhZE8orvsa9aWlXBtgkGSwcd3OHgbs=; b=fbkC1pZeS57D22bcXiX1Cwn4tSxYjyjtUmIBE9kFtWtUxfvi7X9Qv2oekvmXWMy/HV EtifrILKn4YkbcH9m/SmPGD5+D+Qpf5/9gMJfwPfxxc1QKwV3HUhWtz2oeB6QER0w3+V 7ZYPW8T92XHXdsRMNGDVHogLVUAeiRmavIJIEvfmd09MVpcdw3wE0OM5jrY9sMXyHWzz MB30pLSYv8IXfY2CtsZXJ3QCXfwdJK3dVQ4vxsDHFEn5XXvNpeKovDwGzGmv49cebCLG uGfH+LfvdVS/w36S0M3fnh069AQ47D19Q6IuNjXKiXl9Rp2QGPgDBwJSOMpgaRSe5/Sz hw8Q== X-Gm-Message-State: AO0yUKVpLu9O1w3K7jMZeFY2lcW5GjkvTd5Xam83+NfYu1JR/DHOLJc+ b9v1QivvNjKMbt1+BURdBDZCOlYUdrKSRuMw+AUxK9SzBKOQKvgsynq683fvE9SvjPR7y0RkK8l BZbJJSnA8gx14rpio X-Received: by 2002:a05:6a20:3ca0:b0:be:e0c3:5012 with SMTP id b32-20020a056a203ca000b000bee0c35012mr2696229pzj.1.1676947096339; Mon, 20 Feb 2023 18:38:16 -0800 (PST) X-Google-Smtp-Source: AK7set/720MKakE5XCGQ7Uh5rmW8ucJCIgp1rd9sNEeFmTZV4diZNLLhb5dWRXWL+38RQ13GmZ68VA== X-Received: by 2002:a05:6a20:3ca0:b0:be:e0c3:5012 with SMTP id b32-20020a056a203ca000b000bee0c35012mr2696208pzj.1.1676947095997; Mon, 20 Feb 2023 18:38:15 -0800 (PST) Received: from [10.72.13.11] ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id i26-20020aa78b5a000000b005a8e9e2f1c5sm845882pfd.187.2023.02.20.18.38.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Feb 2023 18:38:15 -0800 (PST) Message-ID: Date: Tue, 21 Feb 2023 10:38:10 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [patch net-next] net: virtio_net: implement exact header length guest feature Content-Language: en-US To: Jiri Pirko , "Michael S. Tsirkin" Cc: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, virtualization@lists.linux-foundation.org, Vitaly Mireyno References: <20230217121547.3958716-1-jiri@resnulli.us> <20230217072032-mutt-send-email-mst@kernel.org> <20230217083915-mutt-send-email-mst@kernel.org> <20230220074947-mutt-send-email-mst@kernel.org> From: Jason Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 在 2023/2/20 21:56, Jiri Pirko 写道: > Mon, Feb 20, 2023 at 01:55:33PM CET, mst@redhat.com wrote: >> On Mon, Feb 20, 2023 at 09:35:00AM +0100, Jiri Pirko wrote: >>> Fri, Feb 17, 2023 at 02:47:36PM CET, mst@redhat.com wrote: >>>> On Fri, Feb 17, 2023 at 01:53:55PM +0100, Jiri Pirko wrote: >>>>> Fri, Feb 17, 2023 at 01:22:01PM CET, mst@redhat.com wrote: >>>>>> On Fri, Feb 17, 2023 at 01:15:47PM +0100, Jiri Pirko wrote: >>>>>>> From: Jiri Pirko >>>>>>> >>>>>>> virtio_net_hdr_from_skb() fills up hdr_len to skb_headlen(skb). >>>>>>> >>>>>>> Virtio spec introduced a feature VIRTIO_NET_F_GUEST_HDRLEN which when >>>>>>> set implicates that the driver provides the exact size of the header. >>>>>>> >>>>>>> The driver already complies to fill the correct value. Introduce the >>>>>>> feature and advertise it. >>>>>>> >>>>>>> Signed-off-by: Jiri Pirko >>>>>> Could you add a bit of motivation just for the record? >>>>>> Does this improve performance for some card? By how much? >>>>>> Expected to help some future card? >>>>> I can get that info, but isn't that rather something to be appended to >>>>> the virtio-spec patch? I mean, the feature is there, this is just >>>>> implementing it in one driver. >>>> It is more like using it in the driver. It's not like we have to use >>>> everything - it could be useful for e.g. dpdk but not linux. >>>> Implementing it in the Linux driver has support costs - for example what >>>> if there's a bug and sometimes the length is incorrect? >>>> We'll be breaking things. >>> I understand. To my understanding this feature just fixes the original >>> ambiguity in the virtio spec. >>> >>> Quoting the original virtio spec: >>> "hdr_len is a hint to the device as to how much of the header needs to >>> be kept to copy into each packet" >>> >>> "a hint" might not be clear for the reader what does it mean, if it is >>> "maybe like that" of "exactly like that". This feature just makes it >>> crystal clear. >>> >>> If you look at the tap implementation, it uses hdr_len to alloc >>> skb linear part. No hint, it counts with the provided value. >>> So if the driver is currently not precise, it breaks tap. >> Well that's only for gso though right? > Yep. > > >> And making it bigger than necessary works fine ... > Well yeah. But tap does not do that, does it? it uses hdr_len directly. tap_get_user() limit the head length: static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,                             struct iov_iter *from, int noblock) {     int good_linear = SKB_MAX_HEAD(TAP_RESERVE); ... > > >>> I will add this to the patch description and send v2. >>> >> I feel this does not answer the question yet, or maybe I am being dense. >> My point was not about making hdr_len precise. My point was that we are >> making a change here for no apparent reason. I am guessing you are not >> doing it for fun - so why? Is there a device with this feature bit >> you are aware of? > Afaik real hw which does emulation of virtio_net would benefit from > that, our hw including. Note that driver can choose to no negotiate this feature, so malicious drivers can still try to use illegal value. Thanks > > >> >> >>>> The patch was submitted by Marvell but they never bothered with >>>> using it in Linux. I guess they are using it for something else? >>>> CC Vitaly who put this in. >>>> >>>>>> thanks! >>>>>> >>>>>> >>>>>>> --- >>>>>>> drivers/net/virtio_net.c | 6 ++++-- >>>>>>> include/uapi/linux/virtio_net.h | 1 + >>>>>>> 2 files changed, 5 insertions(+), 2 deletions(-) >>>>>>> >>>>>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>>>>>> index fb5e68ed3ec2..e85b03988733 100644 >>>>>>> --- a/drivers/net/virtio_net.c >>>>>>> +++ b/drivers/net/virtio_net.c >>>>>>> @@ -62,7 +62,8 @@ static const unsigned long guest_offloads[] = { >>>>>>> VIRTIO_NET_F_GUEST_UFO, >>>>>>> VIRTIO_NET_F_GUEST_CSUM, >>>>>>> VIRTIO_NET_F_GUEST_USO4, >>>>>>> - VIRTIO_NET_F_GUEST_USO6 >>>>>>> + VIRTIO_NET_F_GUEST_USO6, >>>>>>> + VIRTIO_NET_F_GUEST_HDRLEN >>>>>>> }; >>>>>>> >>>>>>> #define GUEST_OFFLOAD_GRO_HW_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \ >>>>>>> @@ -4213,7 +4214,8 @@ static struct virtio_device_id id_table[] = { >>>>>>> VIRTIO_NET_F_CTRL_MAC_ADDR, \ >>>>>>> VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \ >>>>>>> VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \ >>>>>>> - VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL >>>>>>> + VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL, \ >>>>>>> + VIRTIO_NET_F_GUEST_HDRLEN >>>>>>> >>>>>>> static unsigned int features[] = { >>>>>>> VIRTNET_FEATURES, >>>>>>> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h >>>>>>> index b4062bed186a..12c1c9699935 100644 >>>>>>> --- a/include/uapi/linux/virtio_net.h >>>>>>> +++ b/include/uapi/linux/virtio_net.h >>>>>>> @@ -61,6 +61,7 @@ >>>>>>> #define VIRTIO_NET_F_GUEST_USO6 55 /* Guest can handle USOv6 in. */ >>>>>>> #define VIRTIO_NET_F_HOST_USO 56 /* Host can handle USO in. */ >>>>>>> #define VIRTIO_NET_F_HASH_REPORT 57 /* Supports hash report */ >>>>>>> +#define VIRTIO_NET_F_GUEST_HDRLEN 59 /* Guest provides the exact hdr_len value. */ >>>>>>> #define VIRTIO_NET_F_RSS 60 /* Supports RSS RX steering */ >>>>>>> #define VIRTIO_NET_F_RSC_EXT 61 /* extended coalescing info */ >>>>>>> #define VIRTIO_NET_F_STANDBY 62 /* Act as standby for another device >>>>>>> -- >>>>>>> 2.39.0